Electric discharge device circuit



Dec. 31, 1935. w. F. WESTENDORP 2,025,408

ELECTRIC DISCHARGE DEVICE CIRCUIT Filed July 21, 19:54

Inveh'bor: Willem F. Westendorp,

is A tornqg Patented Dec; 31, 1935 UNITED STATES PATENT OFFICE- ELECTRICDISCHARGE DEVICE cmourr Willem F. Westendorp, Schenectady, N. Y.,assignor to General Electric Company, a corporation of New YorkApplication July 21, 1934, Serial No. 736,362

9 Claims.

istics in such manner that in one case the cathodes of the devices areheated alone, and in the second case the devices are energized and thecathodes are heated.

15 For a better understanding of my invention, together with other andfurther objects thereof, reference had to the following description,taken in connection with the accompanying drawing, and its scope will bepointed out in the 20 appended claims.

In the accompanying drawing, Fig. 1 illustrates diagrammatically acircuit for electric dischargedevices which are in this case lamps inaccordance with my invention, and Figs. 2, 3

25 and 4 illustrate diagrammatically modifications of my invention.

Referring to Fig. I in detail; 4 and 5 are electric discharge lampspreferably of the type having a container provided with a rare gas and.va 30 vaporizable metal, such as sodium, for example.

Lamp 4 comprises a container 8 an anode 6 and a cathode I. The cathode Iis of the unipotential type having a heater comprising a metal filament9 attached at one end to the cathode 35' surface, the other end beingprovided witlra conductor sealed into the wall of the container 8. Lamp5 is provided with an anode I0, a cathode II, a heater I 2 and acontainer l3. The end of the heater 9 projecting through the wallet the40 container 8 is in accordance with my invention connected to the anode6 by conductor l4 and the corresponding end of heater I2 is connected byconductor l5 to the anode I 0. The cathode 1.

is connected to anode ID by a conductor [6 and the cathode ll may besimilarly connectedto a following lamp in'a series circuit. It isillustrated, however, as being connected to a conductor l1 terminatingin contacts l8 and I9. The anode 6 is connected by a conductor 28 to acontact 2|, which, together with the previously mentioned contacts I8and I9, comprise the stationary contacts for a reversing switch 22. Thereversing switch comprisespivoted blades 23 and 24 connectedrespectively tothe terminals of a 55 direct current generator 25 byconductors 26 and 21. Film cut-outs 28 and 29 are respectively connectedin shunt to the lamps I and 5 and are arranged .to pass current when thelamps break or otherwise become inoperative. 60 In operating devices,connected in the abovedescribed circuits in accordance with myinvention, the switch 22 is thrown to its lower position so as to applya negative potential to the anode 6 and consequently to the succeedinganode I0. With the switch in this lower position, the circuit may betraced from the negative terminal of generator 25, conductor 26, switchblade 23, contact 2|, conductors 20 and I 4, heater 9, cathode 1,conductors l6 and I5, heater l2, cathode ll,

conductor [1, contact l8, switch blade 24., con- 1 ductor 21 to thepositive terminal of the generator 25. A negative potential is therebyapplied to both anodes 6 and I8 and because of the inherentcharacteristic of discharge devices for normally passing current onlywhen positive I potential is applied to the respective anodes, nocurrent will flow across the discharge paths in the two lampsillustrated. The cathode surfaces 1 and II will, however, be heated bythe current flowing through the heaters 9 and I2 which are connected inseries across the generator.

In the operation of this type of lamp it is desirable to preheat thecathodes before applying the operating potential across the-dischargepath of the lamp, that is, from anode to cathode. If.the operatingpotential is applied before the cathode is given a chance to becomeheated to its proper operating temperature, a sputtering of theelectrode material takes place and metal is deposited on the glassenvelopeof the lamp with 30 a consequent reduction in the light emissionof this" envelope and a reduction in the life of the lamp.

When the cathodes have been heated by passing current, as abovedescribed, the reversing switch 22 isoperated to its upper position. Inthis position of the switch positive potential is applied to the anodes.6 and ll) of the lamps and consequently current will flow from the anodeto cathode. Simultaneously current will also flow throughthe filamentheaters 9 and I2 so that with this connection of the generator to thecircuit, the lamps or, in other words their discharge paths, operate inmultiple with the oathode heaters. be traced from the positive terminalof generator 25 through conductor 21, switch blade 24, contact 2| andconductor 20 to anode 6. Current there flows through the vapor and gasesin the envelope 8 to the cathode I. Simultaneously, current flowsthrough conductor M to heater 9 and to the cathode 1.- Both currentsfrom cathode 1 flow through conductor IE to anode l8 and jswitch blade23, conductor 26 to the negative terminal of generator 25. With thisimproved circuit, it is, therefore, possible to preheat the cathodeswithout applying an operating potene The circuit in this instance may 45tial to the lamps, and by simply reversing the connections to thesource, the lamps and the cathode heaters are operated simultaneously.

In Fig. 2 I have illustrated a modification of my invention in which thecathode heaters and the discharge paths of the respective lamps areoperated in series with each other instead of in multiple, as shown inFig. 1. The circuit in Fig. 2 is generally the same as that in Fig. 1,except that a unidirectional connection is applied between the cathodeand the anode of each lamp. Referring to this figure, the direct currentgenerator 25 and reversing switch 22 are connected as in Fig. 1. Arectifier 30 is connected between the conductor 20, leading to anode 6,and cathode 1. The rectifier passes current only in one direction, andthis direction is opposite to the normal current flow between anode 6and cathode '1. When switch 22 is in its lower position, in thisconnection, therefore, current will flow from the positive terminal ofgenerator 25 through conductor 21, switch blade 24, contact|8,.'conductor IT to heater |2. From this heater, current will flow tocathode H and through a conductor 3| to a rectifier 32, similar to therectifier 30, to conductor I6, heater 9, cathode 1, conductor 33 torectifier 30, conductor 20, contact 2|, switch blade 23 and throughconductor 26 to the negative side of the generator. The filament heaters9 and I2 are, therefore, connected in series with each other and currentwill not flow between the cathodes and the anodes, since the positivepotential is applied to the cathode. When the switch 22 is thrown to itsupper position, however, positive potential is applied to the conductor20 and anode 6. Current cannot flow through rectifier 36, since thisunidirectional device is arranged to permit current to flow only in theopposite direction. It acts, therefore, as an insulator and the onlypath open for current to flow is from anode 6 to cathode 1 and thenthrough heater 9, conductor l6 to anode ID. The rectifier 32 is alsoarranged to pass current in the opposite direction and current cannot,therefore, flow through it to the cathode II and the only path open forthe current to flow is the discharge path from anode Hi to cathode Thecurrent in this case may, therefore, be traced from the positiveterminal to generator 25 through conductor 21, switch blade 24, contact2|, conductor 20, anode 6, cathode 1, heater 9, conductor l6, anode l0,cathode ll, heater l2, conductor l1, contact I9, switch blade 23,conductor 26 to the negative side of generator 25. This connection againprovides for a permanent connection of each lamp and its rectifier andit is only necessary to reverse the connection at the source to obtainthe above-described proper operation.

In Fig. 3 I have shown a second modification of my invention in which analternating current generator 35 is used. In this combination a switch36 may be operated to connect the lamps to the source either through atransformer 31 or through a rectifier 38. The cathodes in thisarrangement are illustrated as filaments excited through transformers.When the switch is in position to connect the lamp circuit to the sourcethrough the transformer, the cathode or filament transformers areenergized by a pulsating current obtained in a manner hereinafterexplained.

and when the switch is thrown to connect the lamp circuit to the sourcethrough the rectifier, the lamps are energized by a pulsating directcurrent and the filaments are correspondingly energized by currentsexcited in the secondaries by winding 52.

this pulsating current flowing through the primaries of the cathodetransformers.

Referring to Fig. 3 in detail, lamps 40 and 4| are provided respectivelywith anodes 42 and 43 and filamentary cathodes 44 and 45. The cath- 5ode 44 is connected to the secondary 46 of a filament transformer andcathode 45 is connected to winding 41 of a filament transformer. Arectifier 48 is connected between the anode 42 and the midpoint oftransformer winding 46, and a rectifier 49 is connected between anode 43and the midpoint of transformer winding 41. The secondary winding 46 isenergized by current flowing in primary winding 5| and the winding 41 isenergized by current flowing in primary 15 When switch 36 is thrown toits lower position, current will fiow from generator 35 throughtransformer 31 to the switch 36, which is provided with two blades 53and 54. From blade 54, current flows through conductor 20 55, primarywinding 52, conductor 56 through rectifier 49, conductor 51, primarywinding 5|,

conductor 58, rectifier 48, conductor 59, switch blade 53 to transformerwinding 31. The rectifiers 4B and 49 are arranged to pass only one- 25half wave of the alternating current furnished by transformer 31. Thisis the negative half wave. The positive half-wave is impressed upon theanodes 42 and 43, but these half waves are of a low voltage and will notinjure the lamp and the 30 cathodes are sufliciently heated by the otherhalf wave. When switch 36 is thrown to its upper position, a pulsatingdirect current will be applied to the circuit in such manner that the"positive terminal will be connected to switch 35 blade 53. Current willthen flow from rectifier 38 to switch blade 53, conductor 59, to anode42, cathode 44, winding 46, conductor 56 and winding 5|, one end ofwhichis connected to conductor 56. Generally it is attempted to smooth40 out the output current of a rectifier by placing inductances inseries therewith. In the present case this pulsating characteristic istaken advantage of and in some instances aggravated to excite thewindings 46 and 41 and thereby generate sufiicient heat in addition tothat caused by the discharge current, to properly heat the cathodes 44and 45. The rectifiers 48 and 49 do not pass current in this case. Fromwinding 5| current flows to conductor 51, anode 43, cathode 45, winding41, conductor 56, winding 52, conductor 55, switch blade 54 to thenegative side ofthe rectifier 38.

In Fig. 4 I have shown a slight modification of Fig. 1 in which theswitch 22 is not used as a 55 reversing switch but merely to include orexclude a shunt resistance from the circuit; When the switch is in itslower or preheating position the switch blade 23 engages contacts 60 and6| connected to the conductor 20 and to one end of a resistor 62respectively. The switch blade 24 engages contacts 63 and 64. Thecontact 63 is connected to the conductor I1 and the contact 64 isconnected to the other end of resistor 62. In this position of theswitch the resistance 62 lowers the current in the series circuit due tothe constant current in the generator circuit and consequently thepotential across each lamp. The lowered potential is substantially equalto the operating potential of the lamps and is, 70 therefore, suificientto force the proper heating current through the cathodes. When switch 22is moved to its upper position, the potential across the lamps is raisedmomentarily, the discharge is started and the current then flows.cathode, a rectifier connected between the anode through the cathodeand discharge path in multiple. I Although I have described my inventionas applied to lamps, it will be apparent to those skilled in the'artthat it is equally applicable to other electric discharge devices, suchas rectifiers for example.

Furthermore, the lamps indicated in the accompanying drawing may beeither the cathode glow type of lamp or they may be the positive columntype of lamp. The invention is applicable to all discharge deviceswherein it is desired to heat the cathodes before passing dischargecurrent from anode to cathode.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

1. In combination, a plurality of series connected electric dischargedevices, each device being provided with an anode, a thermionic cathodespaced therefrom, and a heating circuit for said cathode connected inshunt to said spaced electrodes, a current source, electricalconnections for said series circuit to said source so as to provide acurrent of predetermined characteristic to heat only said cathodes inseries, and

means for thereafter changing said connection to provide current ofanother characteristic for simultaneously causing a discharge betweensaid electrodes and'for heating said cathodes.

2. In a lighting circuit, the combination of a direct current source, aplurality of electric discharge lamps, each having an anode and a ther-,

mionic cathode, a connection from each cathode to the anode of thefollowing lamp, a conductive connection between each anode and itscorresponding cathode, means for connecting said lamps to said source soas to cause a current flow in a direction opposite to the normal flow ofcurrent between the electrodes of each lamp for preheating the cathodes,and. means for thereafter changing the direction of the current flow soas to cause a discharge between said electrodes and for heating saidcathodes.

3. In combination, a direct current source, a plurality of electricdischarge devices, each provided with an anode, a cathode spacedtherefrom, an envelope containing a rare gas and a conductive connectionbetween said anode and one end of said cathode, a conductive connectionbetween the other end of each cathode and the anode of the followinglamp whereby said cathodes are connected in series, a reversing switchfor applying a negative potential to said anodes whereby the cathodesare heated and for subsequently reversingsaid potential whereby adischarge current flows between said spaced electrodes respectively andthrough the cathodes in multiple with said discharge current. I

4. In a lighting circuit, the combination of a direct current source, anelectric discharge lamp provided with an anode, a cathode spacedtherefrom anda unidirectional device connected in multiple to saidelectrodes and arranged to permit current flow in a direction oppositeto the normal current flow 'between said anode and cathode, a reversingswitch for applying current to said lamp from said source in a directionopposite to the normal current flow wherebythe cathode alone is heatedand for thereafter reversing said current to cause a discharge cur-'rent to flow between said electrodes and cathode in series.

I 5. In a lighting circuit, the combination of a. pluraiityof electricdischarge lamps, each lamp being provided with an anode and a thermionicheaters. Y

said source to said circuits and for subsequently reversing theconnection whereby the cathodes are first energized in series with eachother through said rectifiers and subsequently-upon reversal of thecurrent are energized by the current flowing across the discharge pathfrom said anode to cathode and through the cathode to the anode of thefollowing lamp.

6. In a lighting circuit, the combination of a plurality of electricdischarge lamps, each being provided withan anode, a thermionic cathodeand a unidirectional connection between anode and cathode for passingcurrent in a direction opposite to the normal current flow from anode tocathode, within the lamp, a connection from each cathode to the anode ofthe following lamp,

a source of alternating current and a source of pulsating directcurrent, means for connecting said alternating circuit to said lamps forenergizing the cathodes, and means for thereafter connecting thepulsating direct current source to said circuit for energizing both thecathodes and the anode to cathode circuits.

7. .In alighting circuit, the combination of a plurality of seriesconnected electric discharge lamps, each lamp being provided with ananode, a cathode and a heater for said cathode, a connection includingsaid heater in shunt to said electrodes, a current source, means forconnecting said series circuit to said source so as to provide a currentof predetermined characteristic to energize said cathode heaters inseries, and means for thereafter changing said connection so as toprovide current of another characteristic for causing a dischargecurrent to flow between said electrodes and through said cathodes inmultiple.

8. In combination, a plurality of series connected electric dischargedevices, each device being provided with an anode,- a thermionicfilamentary cathode spaced therefrom and a conductive connectionincluding said cathode in shunt to said spaced electrodes, a currentsource, means for connecting said circuit to said source and applying apotential which is-below the breakdown potential across the electrodesin each device whereby current will flow through said ingprovided withan anode, a cathode and a heater for said cathode, a connectionincluding said heater in shunt to said electrodes, a current source,means for connecting said series circuit to said source and applying apotential which is below the breakdown potential between the electrodesof said devices'whereby the said heaters alone are energized and forsubsequently increasing said potential to the breakdown potential ofsaid devices whereby a discharge current is caused to flow between saidelectrodes in multiple with the current flowing through said WILLEM F.WESTENDORP.

